**1. Introduction**

Although sugarcane (*Saccharum* spp.) has been traditionally cultivated for sugar production, it has emerged in the past few decades as one of the best crops for biofuel production [1]. Currently, world sugarcane production is close to 1.6 billion tons annually and is concentrated in the tropical regions, particularly in the developing nations in Latin America, Africa, and Asia [2] (**Figure 1**). Brazil is the world's largest sugarcane producer, followed by India, China, Pakistan, Thailand, and Mexico. As a result of the increased economic importance of sugarcane, the requirements for large-scale production in an environmentally sustainable manner have also increased. However, massive planting of the crop brings environmental risks that include a potential impact on tropical soil ecosystem sustainability (**Figure 1**), which is still an open question for soil microbes and microbial-mediated processes that lead to greenhouse gas (GHG) emissions.

sugar-ethanol industry, also known as stillage [6]. Its chemical composition varies depending on the mill plant used for the production of ethanol and the distillation process [7]. In general, sugarcane vinasse is composed of water (93%) and organic solids and minerals (7%) [7]. It has high levels of organic matter but is low in N and P. The main non-water component of sugarcane vinasse is organic matter that exists in the form of organic acids and cations such as K, calcium (Ca), and magnesium (Mg) [7]. Since the 1960s, vinasse has been used as a liquid fertilizer in the sugarcane fields of Brazil to solve the ecological problem of its disposal within the environment. Studies from the late 1980s have recommended the use of N fertilizer in combination with vinasse in sugarcane fields [8], and a more recent study has recommended

Multi-Analytical Interactions in Support of Sugarcane Agroecosystems Sustainability in Tropical…

http://dx.doi.org/10.5772/intechopen.71180

5

The inorganic and organic fertilizer amendments, primarily used to increase nutrient availability to plants, and the management of sugarcane harvest residue are likely to affect the physical [10, 11], chemical [10, 12–14], and microbiological [13–21] attributes of sugarcane soils as well as the GHG emissions from sugarcane areas [19, 22–26]. Soil microbes comprise a major fraction of the total living soil biomass [27]. Many of the abovementioned studies have highlighted that numerous microbial groups are highly correlated with specific soil factors. The studies reported differences in the soil microbial community related to management practices for sugarcane due to the effects of soil factors. Despite increased attention to the soil microbial community and its relationship with soil characteristics in sugarcane-cultivated areas, little progress has been made in elucidating the implications of the agricultural prac-

tices on the functional roles of this community in tropical sugarcane agriculture [16].

for supporting the sustainable development of biofuel production.

**2. Nutrient management and soil amendments**

analytic perspective.

With this in mind, this chapter was aimed at examining the available data on the subject as a contribution to update the knowledge on the benefits and risks of nutrient management and soil amendments as well as of crop residue and harvest management in sugarcane soils on belowground microbial life, soil physical and chemical factors, and biogeochemical processes mediated by soil microbial communities. We summarize, in this chapter, the impacts of these management practices on soil microbes at multiple ecological levels, on soil physicochemical attributes including labile fractions from soil organic matter and on GHG emissions (mainly nitrous oxide due to nitrogen losses in sugarcane production systems). Based on multi-analytical interactions, we emphasize that soil management and harvest management are critical

Sugarcane is a semi-perennial crop replanted after 3–7 ratoon cycles, depending at least in part on the soil fertility and crop variety [5]. After a relatively long time receiving fertilizers and recycling crop residue on an annual basis, the soil ecosystem sustainability and multifunctionality can become compromised in most production areas [28]. The impacts of these management practices, and inorganic and organic fertilizer amendments on soil microbes and GHG emissions, as well as on soil physicochemical factors including labile fractions from soil organic matter in sugarcane fields worldwide are addressed below based on a soil multi-

the use of N fertilizer with straw retention [9].

Soil functions are effective only as long as the capacity for the interactions between the physical, chemical, and biological processes is preserved. The increased need for fertilizers due to the expansion of sugarcane production is a threat to the ability of the soil to maintain its potential for self-regulation in the long term, i.e., its sustainability [3]. Soil management practices used in sugarcane agriculture require synthetic mineral fertilizers (nitrogen/phosphorus/potassium—NPK) [4] and full recycling of waste products from the ethanol production to sugarcane fields in the form of organic fertilizer [5]. Sugarcane vinasse is a by-product of the

**Figure 1.** Infographic of the belowground-atmospheric potential impacts of large-scale sugarcane production from a soil ecological and integrated perspective. The map shows sugarcane production in the world. Gas emissions from combustion are shown from burning harvest. Carbon dioxide (CO<sup>2</sup> ) emissions are shown from fossil fuel combustion aboveground.

sugar-ethanol industry, also known as stillage [6]. Its chemical composition varies depending on the mill plant used for the production of ethanol and the distillation process [7]. In general, sugarcane vinasse is composed of water (93%) and organic solids and minerals (7%) [7]. It has high levels of organic matter but is low in N and P. The main non-water component of sugarcane vinasse is organic matter that exists in the form of organic acids and cations such as K, calcium (Ca), and magnesium (Mg) [7]. Since the 1960s, vinasse has been used as a liquid fertilizer in the sugarcane fields of Brazil to solve the ecological problem of its disposal within the environment. Studies from the late 1980s have recommended the use of N fertilizer in combination with vinasse in sugarcane fields [8], and a more recent study has recommended the use of N fertilizer with straw retention [9].

**1. Introduction**

4 Sugarcane - Technology and Research

**N2**

**N O**

**Nitrifying Denitrifying**

aboveground.

**Combustion Fossil fuel**

**combustion**

Although sugarcane (*Saccharum* spp.) has been traditionally cultivated for sugar production, it has emerged in the past few decades as one of the best crops for biofuel production [1]. Currently, world sugarcane production is close to 1.6 billion tons annually and is concentrated in the tropical regions, particularly in the developing nations in Latin America, Africa, and Asia [2] (**Figure 1**). Brazil is the world's largest sugarcane producer, followed by India, China, Pakistan, Thailand, and Mexico. As a result of the increased economic importance of sugarcane, the requirements for large-scale production in an environmentally sustainable manner have also increased. However, massive planting of the crop brings environmental risks that include a potential impact on tropical soil ecosystem sustainability (**Figure 1**), which is still an open question for soil microbes and

Soil functions are effective only as long as the capacity for the interactions between the physical, chemical, and biological processes is preserved. The increased need for fertilizers due to the expansion of sugarcane production is a threat to the ability of the soil to maintain its potential for self-regulation in the long term, i.e., its sustainability [3]. Soil management practices used in sugarcane agriculture require synthetic mineral fertilizers (nitrogen/phosphorus/potassium—NPK) [4] and full recycling of waste products from the ethanol production to sugarcane fields in the form of organic fertilizer [5]. Sugarcane vinasse is a by-product of the

**Soil microbes**

**Soil physics**

**Crop residues**

**Soil moisture**

**Figure 1.** Infographic of the belowground-atmospheric potential impacts of large-scale sugarcane production from a soil ecological and integrated perspective. The map shows sugarcane production in the world. Gas emissions from

**O.M. Soil chemistry** **Burning harvest**

**Microbial respiration and decomposition**

) emissions are shown from fossil fuel combustion

**Green harvest**

Above ground

Below ground

F F

**Organic and inorganic fertilizer amendments**

microbial-mediated processes that lead to greenhouse gas (GHG) emissions.

**O CH4 CO2**

**Methanotroph**

**Sugarcane**

**Uptake by plant**

combustion are shown from burning harvest. Carbon dioxide (CO<sup>2</sup>

The inorganic and organic fertilizer amendments, primarily used to increase nutrient availability to plants, and the management of sugarcane harvest residue are likely to affect the physical [10, 11], chemical [10, 12–14], and microbiological [13–21] attributes of sugarcane soils as well as the GHG emissions from sugarcane areas [19, 22–26]. Soil microbes comprise a major fraction of the total living soil biomass [27]. Many of the abovementioned studies have highlighted that numerous microbial groups are highly correlated with specific soil factors. The studies reported differences in the soil microbial community related to management practices for sugarcane due to the effects of soil factors. Despite increased attention to the soil microbial community and its relationship with soil characteristics in sugarcane-cultivated areas, little progress has been made in elucidating the implications of the agricultural practices on the functional roles of this community in tropical sugarcane agriculture [16].

With this in mind, this chapter was aimed at examining the available data on the subject as a contribution to update the knowledge on the benefits and risks of nutrient management and soil amendments as well as of crop residue and harvest management in sugarcane soils on belowground microbial life, soil physical and chemical factors, and biogeochemical processes mediated by soil microbial communities. We summarize, in this chapter, the impacts of these management practices on soil microbes at multiple ecological levels, on soil physicochemical attributes including labile fractions from soil organic matter and on GHG emissions (mainly nitrous oxide due to nitrogen losses in sugarcane production systems). Based on multi-analytical interactions, we emphasize that soil management and harvest management are critical for supporting the sustainable development of biofuel production.
